Many here are planning to get the aluminum Sport model and one of the bands from the stainless steel collection to wear to nicer occasions. However, all the non-Sport bands (except the Leather Loop) house stainless steel connectors, and we know that aluminum and stainless steel together poses a bi-metallic corrosion risk, also known as galvanic corrosion, especially in the presence of sweat (from working out or just from wearing the watch on a hot day).

"Bands work with all collections but may not match the finish or be optimal for use with that specific collection."

The bold part seems to indicate that galvanic corrosion is a potential problem, especially when the anodized coating inside the aluminum connectors get worn down and you wear it with the stainless steel bands while working out or on a hot day.

If corrosion does become a problem that's gonna suck and be a huge disappointment to many people. I wonder if Apple plans to mention this to customers when they buy a metal band. It is on the training material which has me thinking they will.

Can attest that this can be a problem when I got the original Nike fuel band with aluminum screws on the inside of the band ... corroded to the point that the casing opened. Complained to Nike and got a free SE version of the fuel band.

Anodizing aluminium starts out much like titanium. Using aluminum as the positive electrode, engineers first pass enough current to grow a thin "barrier" layer - similar to that which forms naturally. Then, as the anodizing proceeds, the current "pushes" this barrier deep down into the aluminum converting the aluminum above into a very porous oxide layer. It isn't a layer being put on top, but instead the reaction consumes and converts the aluminum; this is one of the reasons it's so effective at preventing corrosion. The pores in this layer give the aluminum a unique characteristic important for a consumer device: The ability to be colored. The pores formed on the surface have a honeycomb pattern. Inside these layers one can place dye of any color. Once the pores are filled engineers seal the layer by boiling the aluminum in hot water. This closes the pores, locking the color in forever, you cannot scrape it off without removing the aluminum. The toughness comes from the oxide being structurally similar to tough gemstones. Sapphire is an aluminum oxide - with trace amounts of iron and titanium to give it a blue color; it's also the basis of ruby, the same crystal structure with chromium that absorbs yellow-green. Both materials are very hard: Nine on the Mohs scale.

"Bands work with all collections but may not match the finish or be optimal for use with that specific collection."

The bold part seems to indicate that galvanic corrosion is a potential problem, especially when the anodized coating inside the aluminum connectors get worn down and you wear it with the stainless steel bands while working out or on a hot day.

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Not to discount what you're saying, but I think you're reading an awful lot into a fairly innocuous statement. I would hope that if this is really a concern that they would have a more carefully-worded warning about corrosion than something as incredibly vague as what you quoted.

Not to discount what you're saying, but I think you're reading an awful lot into a fairly innocuous statement. I would hope that if this is really a concern that they would have a more carefully-worded warning about corrosion than something as incredibly vague as what you quoted.

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I agree. I think the statement is more about clashing looks than it is about corrosion.

Not if it is Anodizing Aluminium as in the Apple Watch case (similar with unibody iPhone, Macbook, iMac).

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You do know that the anodized coating is prone to wearing off, as we've seen numerous times especially with the black and slate iPhone 5. It's going to get even worse inside the aluminum connectors from repeatedly sliding the hinges in and out when swapping bands.

Not to discount what you're saying, but I think you're reading an awful lot into a fairly innocuous statement. I would hope that if this is really a concern that they would have a more carefully-worded warning about corrosion than something as incredibly vague as what you quoted.

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I didn't say it is direct evidence, only an indication that it's a potential problem. Who knows what else is inside the training materials as we don't have access to them?

Many here are planning to get the aluminum Sport model and one of the bands from the stainless steel collection to wear to nicer occasions. However, all the non-Sport bands (except the Leather Loop) house stainless steel connectors, and we know that aluminum and stainless steel together poses a bi-metallic corrosion risk, also known as galvanic corrosion, especially in the presence of sweat (from working out or just from wearing the watch on a hot day).

"Bands work with all collections but may not match the finish or be optimal for use with that specific collection."

The bold part seems to indicate that galvanic corrosion is a potential problem, especially when the anodized coating inside the aluminum connectors get worn down and you wear it with the stainless steel bands while working out or on a hot day.

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Only an insane person would buy a Sport and a SS band that costs more than the watch. Therefore, most people won't experience this problem.

I didn't say it is direct evidence, only an indication that it's a potential problem. Who knows what else is inside the training materials as we don't have access to them?

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It's only an indication that corrosion might be a problem if you're already expecting it might be. No one who isn't already concerned about it would even begin to think that's what that statement was indicating, IMO.

Again, I'm not saying you're wrong, I just think you're jumping to conclusions.

It's only an indication that corrosion might be a problem if you're already expecting it might be. No one who isn't already concerned about it would even begin to think that's what that statement was indicating, IMO.

Again, I'm not saying you're wrong, I just think you're jumping to conclusions.

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Maybe, but we do know that aluminum and stainless steel together poses a bi-metallic corrosion risk so it's reasonable to expect that, especially in the presence of sweat.

Only an insane person would buy a Sport and a SS band that costs more than the watch. Therefore, most people won't experience this problem.

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First of all, the leather classic and modern buckle bands and the Milanese loop band don't cost more than the Sports watch.

Second, never presume what most people will do. Yes, some people might stop and think about how much the band costs in proportion to the watch, but others might just think about the cost of the entire package. After all, it's a matter of looks and feel (how it feels when worn on the wrist). People are willing to pay a lot for something they wear, because they want to look and feel good.

Maybe, but we do know that aluminum and stainless steel together poses a bi-metallic corrosion risk so it's reasonable to expect that, especially in the presence of sweat.

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If this is a real concern, I would expect Apple to put a much stronger warning -- even make it so that the steel bands can't physically fit the aluminum case. Otherwise, they are looking at a massive "corrosion-gate."

While I'm not going to pretend that I have a great in-depth knowledge about this subject (more of an organic chemist myself), I highly doubt it will be an issue. Apple really won't want something like this (which, if it did corrode, would make great fodder for the media due to the immediate cosmetic issue) to become the Apple Watch's "-gate". I'm sure they've tested it, especially after the LG G Watch had an issue with galvanic corrosion.

I'm not even sure how much of the band touches the case - it looks like there are a couple of rubber bits on the band to keep them separated - never mind being enough to scrape away the metal to reveal the non-anodised aluminium.

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